This invention is directed in general to the field of audiology and digital sound engineering and in particular to a system and method for enhancing user experience based on an individualized audiological profile.
Hearing loss has been estimated to be the most prevalent disability in developed countries. Literally millions of people worldwide suffer from hearing disabilities, many of whom are unaware of their hearing loss. The decreased hearing capability may be due to several factors, including age, health, occupation, injury and disease. The loss of hearing can lead to significant reductions in quality of life, impaired relationships, reduced access to employment and diminished productivity. Different types of hearing loss and related conditions can affect people's daily activities in different ways, in particular having phone conversations and listening to music.
In general, hearing sensitivity to high-pitched sound tends to lessen first. People generally are not aware of the decrease in their hearing sensitivities until they experience hearing problems, for instance, difficulty understanding a conversation on the phone or having problems hearing in a noisy environment. For people with hearing deterioration, their hearing capabilities are generally sufficient for most listening situations. Since the impact of their hearing loss is tolerable, they tend to ignore or find a way around it. They might avoid talking on the phone in noisy environments and would unlikely seek help from a hearing healthcare professional. Individuals with significant hearing loss may consult a hearing healthcare professional to be prescribed and procure a hearing aid. Although wearing a hearing aid is considered as one of the less intrusive assistive technologies for hearing loss patients, it is not without problems. To use a hearing aid during a phone conversation or music enjoyment via headphones is clumsy and inconvenient. People using a hearing aid often experience feedback, the squeal created by the hearing aid output sound being picked up by the hearing aid microphone.
A common problem associated with hearing loss is tinnitus. Tinnitus is a conscious experience of sound that originates in the head (i.e., without an external acoustic source) and may be manifest by an evident audible ringing that interferes with other sounds around one or more frequencies. Tinnitus is a common condition and a symptom normally observed with age-related hearing loss. Tinnitus is known to affect individuals to varying degrees and in a great number of different ways. Some people with chronic tinnitus are able to ignore the condition while others find it annoying, intrusive, distracting, and even disabling. Tinnitus may interfere with sleep, causing both emotional distress and other ill-effects on general health.
Many tinnitus sufferers notice that their tinnitus changes in different acoustic surroundings; typically, it is more bothersome in silence and less annoying in sound-enriched environments. This phenomenon has led to the development of sound therapies for tinnitus treatment. The most common recommendation is to “avoid silence” by enriching the background sounds. This can be accomplished by simply playing some background sound or music. More sophisticated sound therapies involve measuring the pitch and loudness of the tinnitus signals and providing signals which can be played via ear level devices and sound generators.
One of the aspects of the invention is hearing profiling, particularly through self-administered testing. During hearing profiling, minimum audible hearing levels for a set of audiometric frequencies are measured. Various methods are known for obtaining minimum audible hearing levels. During application of hearing profiling to a hearing enhancement device (such as a hearing aid, sound amplifier, or personal listening device such as an MP3 player, a smart phone or the like) in a specific situation, however, a person at times may insist on increasing or decreasing device volume in order to sufficiently hear and comprehend otherwise enhanced audio as determined by hearing tests and corresponding modification of the hearing profile at the ear as part of the sound enhancement process. One problem is that the unintentional induced loudness in the enhanced audio may cause hearing discomfort and damage. A person may have a higher tolerance level for a certain audiometric frequency while having a lower tolerance level for another frequency. A person's sound loudness tolerance profile differs from person to person. The difference may not be very significant among people with normal hearing. However, it is not the case for people with various degrees of hearing impairments, such as hearing loss, tinnitus, and hearing loss with tinnitus. Due to the difference in people's sound loudness tolerance profiles, the hearing curve of a person with normal hearing should not be used as the standard. Thus, fitting of a person's hearing curve without taking into consideration the person's sound loudness tolerance profile may lead to hearing discomfort or damage.
Simply increasing device volume in order to sufficiently hear and comprehend enhanced audio as governed by the sound enhancement process may be dangerous. Increasing or decreasing device volume implies amplifying or de-amplifying audio of all audiometric frequencies by the same factor. A person typically requires amplifying or de-amplifying a limited range of audiometric frequencies. Increasing or decreasing the loudness of audio of all audiometric frequencies may lead to a range of hearing problems. A system capable of handling the various sound loudness tolerance profiles with various degrees of hearing impairments is needed. More specifically, solutions to the problems identified herein, such as hearing difficulties during phone conversations or while listening to music, as well as feedback created by use of a hearing aid, are needed.
Conventional “hearing tests” require a calibrated device to measure the hearing threshold level of an individual in a quiet environment. The data set captured from such hearing tests thus represents the threshold values of an individual's hearing.
In order for a device to produce a specific sound wave amplitude as a test tone, the device and its transducer combination require calibration. The reason for this is that the circuitry and transducer or earphone of each device have different frequency responses that influence the output amplitude of sound waves. This means the same electric audio signal will result in different amplitudes of sound waves for devices and earphones of different models. Therefore, by calibrating the device and the earphone combination, specific sound wave amplitudes as test tones can be produced for hearing testing purposes.
By using a calibrated device, consistent sound wave amplitudes can be produced and the accurate value of hearing levels can then be obtained by finding the thresholds over a range of frequencies in a sound-proof or quiet environment, and producing a “hearing profile” which will represent a subject's hearing threshold or audiogram. The inventors' work on this aspect has been published in The International Journal of Audiology Vol. 51, No. 8, p 606-610 (August 2012). The data thus captured within the device may then be used as parameters based upon which the signal processing engine can modify or enhance the audio signal.
During development, experiments were carried out and results from individuals with “normal” hearing and individuals with hearing loss over a range of frequencies revealed there are factors which are important and should be taken into account during audio signal enhancement. Among these factors are transducers in the earphones and environmental noise. Further investigation using various earphones which differ from the calibrated (standard) earphone confirmed the importance of the “transducer effect.” Indeed, any electronic component, whether substituted for another component or added to/removed from a calibrated signal pathway may contribute to the transducer effect. For example, the inventors have found that even two units of the same Samsung Galaxy Tab® model, but made in different years and bearing different sound cards, can have slightly different audio properties.
It was found that using different earphones, the same user's profiles obtained could differ slightly between the various models of earphones. The differences are due to the different frequency responses of the earphone's transducer compared with the transducer of the earphone for which the system was calibrated.
During development, experiments were carried out that revealed that background environment noise also affects the individual abilities to perceive or understand the acoustic signals. This is due to the “masking effect” of the background noise. If the environment noise is analyzed and then taken into account during audio signal enhancement, this can be configured to provide benefits to the user.
By taking into account both the transducer effect and environment, additional information/data may be collected and stored aside from the threshold values obtained. This data is specific to the transducer used, as well as the environment noise composition at the time of data collection. The transducer characteristics can even be determined by the user indicating to the system the brand/model of the earphone before undergoing the test protocol. The environment noise can be separately sampled and analyzed during the test.
In view of the foregoing, it will be understood that isolating the characteristics of a particular user's audio perception requires accounting for a number of audio device characteristics, as well as either controlling or accounting for environmental noise. These requirements add complexity to the data acquisition and/or processing components needed in a profiling system. A need therefore exists for a more practical and efficient system and method of providing customized enhanced sound for a particular user. Further, different users may have sound enhancement preferences that are determined by other considerations than frequency-specific audio perception, comfort levels, or tinnitus, including personal aesthetic taste, for example. Thus, there is also a need for a sound enhancement system that permits a user to manually adjust the audio output of a device, starting from an automatically produced default enhanced signal.